4.5 Hideous Cloud - PeachParts Mercedes-Benz Forum

joshhol · #1 08-27-2003, 06:11 PM

I did a search before asking and it is confirming what I believe, valve stem seals need replacing.

The 280 4.5 emits a hideous cloud of bilge on start up. Each and every start up, sometimes worse that others. It is whitish gray in color and smells like burnt oil. It is quite embarrassing. Perhaps the exhaust police are going to come one day and haul old bilgey away.
I don't have any records on the car, don't know the mileage. I think its the original engine. There is a little bit of blow by leaving a stop sign and some minor clouds at an idle. It also smokes badly if decelerated quickly from a high speed.
If that is from bad rings than I'd imagine quite a bit of mileage on the engine. It is possible given the very ratty nature of it's appearance. It's definitely in the golden years of its life.
I asked my mechanic about it and he said new valve stem seals would only cure it for about 6 months. I don't want to rebuild the top end, this car is just to be driven with minimal investment.
Does it need new valve guides and stem seals to solve this?
I just want to cure the smoking at startup.
Pulling the head off would be over my head. What can I do at home to fix this. Thanks

deepbluex · #2 08-27-2003, 07:18 PM

It sounds like a mixture of oil as well as coolant. Coolant leaks cause white smoke and a somewhat sickly sweet odor.

psfred · #3 08-27-2003, 09:20 PM

Usually bad valve stem seals only cause a small puff of smoke on startup and excessive oil consumption. How much oil are you using?

I'd bet the guides are worn too -- typically the heads need work about 250,000 miles on this engine.

Peter

joshhol · #4 08-28-2003, 10:02 PM

Quote:

Usually bad valve stem seals only cause a small puff of smoke on startup

Well, it is anything but a small puff of smoke.
I'm assuming valve guide replacement requires pulling the head. If so, I'll just do stem seals and see how that helps.
As far as the coolant leaking, wouldn't it smoke longer during the warmup? It does not.
It does use some oil, but not a ridiculous amount. If I top off the oil, it leaks about half a quart quickly and then remains there for a while. Estimate a quart every. . . 600-700 miles. Dont know for sure.
This car wouldn't be a bad guinea pig for me to buy an engine manual and pull the head myself, if you guys talk me into it.

I have access to a shop where people DIY.

300SDog · #5 08-29-2003, 06:53 AM

Josh, seals usually let go before valve guides wear down. Ignored valve seals might lead to valve guides letting go. Seals on 6 cyl. engine usually give up the ghost between 120 - 150k miles. How many miles on the engine?

The coolant suggestion could be in referrence to V-8s blowing head gaskets, not rare thing to happen.... And if coolant is mixing with oil, your apparent oil level wont diminish!! Try checking the oil with engine running - small bubbles on oil stick can indicate coolant / oil leak at head gasket. Also you might find oil mixed with coolant in radiator. This is worst case possible scenario, you understand.

Pulling the heads is easy - if thats what you gotta do...... but it takes machine shop to press-fit new valve guides. Also let the shop order their own MB valve guides, in case they need to drill out for oversize guides.

joshhol · #6 08-29-2003, 02:35 PM

Dieseldog, thanks

Engine mileage unknown. Best estimate - a lot.

Re coolant leak. No oil bubbles in radiator, no milky color of oil.
Smoke only at the tickover of the engine.
Sounds like guides and seals bad.
I'm sure a top end rebuild would help a lot. I bought the car for $500, dont want to do much to it but may consider pulling head for the experience.
How do I know if lower end is shot? Will a leak down test isolate the condition of the rings?
Can I just redo the guides and seals, or is it economical at that point to do a whole valve job?
thanks again
Josh